Who developed the geocentric theory?

Ptolemy of Alexandria

Explanation:

Ptolemy of Alexandria

Explanation:

The most highly developed geocentric model was that of Ptolemy of Alexandria (2nd century ce). It was generally accepted until the 16th century, after which it was superseded by heliocentric models such as that of Nicolaus Copernicus.

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the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).